## GENC: Generate Covariance Matrix Header

This record specifies that the covariance matrix (for 2DC, 2DD, 3DC, and 3DD observation sets) is to be generated. This method of generating the observation covariance matrix should only be used for simulating networks and is not meant to be a replacement for an actual covariance matrix. The format of the GENC record is as follows:

The coordinate system types are:

All additive values (for entire matrix, for diagonal elements, and PPM) are applied to the matrix first, then the factors are applied. All addition constants are added directly to the covariance matrix (no squaring takes place). The PPM value is used to compute a standard deviation which is then squared before adding it to the diagonal elements of the covariance matrix.

**Columns 002-005**: GENC**Columns 007-008**: Coordinate system of covariance matrix (LG or CT)**Columns 010-013**: Matrix form (UPPR or DIAG)**Columns 015-024**: Addition constant for entire covariance matrix**Columns 026-035**: Scale factor for entire covariance matrix**Columns 037-046**: Addition constant for diagonal of covariance matrix**Columns 048-057**: Scale factor for diagonal of covariance matrix**Columns 059-068**: PPM addition for diagonal of covariance matrix**Columns 070-079**: Addition constant for height/Z**Columns 081-090**: Scale for height/Z**Columns 092-093**: Linear unit nameThe coordinate system types are:

**LG**: Local geodetic (North, East, Up)**CT**: Conventional Terrestrial (Geocentric X, Y, Z)All additive values (for entire matrix, for diagonal elements, and PPM) are applied to the matrix first, then the factors are applied. All addition constants are added directly to the covariance matrix (no squaring takes place). The PPM value is used to compute a standard deviation which is then squared before adding it to the diagonal elements of the covariance matrix.